Polishing pad having hollow fibers and the method for making the same

ABSTRACT

The invention relates to a polishing pad having hollow fibers and a method for making the same. The polishing pad comprises a body and a plurality of hollow fibers. The body has a polishing surface. The hollow fibers are located within the body and have an opening on the polishing surface, wherein the hollow area of the section of each hollow fiber is larger than the sectional area of polishing particles in a polishing slurry. Therefore, the polishing slurry and polishing particles achieve a thorough circulation on the polishing pad via the hollow fibers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing pad for use in a chemical mechanical polishing (CMP) process and the method for making the same, and more particularly, to a polishing pad having hollow fibers and the method for making the same.

2. Description of the Related Art

Generally speaking, grinding refers to the abrasion loss control for the originally rough surface in the chemical mechanical polishing (CMP) process, wherein the polishing slurry containing polishing particles is uniformly dispersed on a top surface of a polishing pad, and meanwhile, a workpiece to be ground is pressed against the polishing pad and then is rubbed repeatedly and regularly. The workpiece to be ground is an object such as a semiconductor, a storage medium substrate, an integrated circuit, an LCD flat glass, an optical glass or a photoelectrical panel. In order to maintain the distribution and the flow of the polishing slurry, and to maintain the flattening and the polishing efficiency after the CMP process, a plurality of grooves is opened on the top surface of the polishing pad or a surface pattern is always formed thereon. Therefore, the grinding effect of the polishing pad on the object to be ground is easily influenced by the grooves or the surface pattern.

Referring to FIG. 1, it is a schematic top view of a conventional polishing pad having a surface pattern. The surface pattern of the polishing pad 1 comprises a plurality of linear grooves 11 arranged in a “#” shape, wherein the depth, width, and space of the linear grooves 11 are designed depending upon actual requirements. The linear grooves 11 have preferred uniformity with respect to the polishing pad 1, and may provide preferred flowability of the polishing slurry. However, since there are many channels communicating with the periphery 12 of the polishing pad 1, the area occupied by the grooves 11 takes up a large percentage of the whole grinding area, thereby causing the loss of a large amount of polishing slurry.

FIG. 2 is a schematic top view of a second conventional polishing pad having a surface pattern. The surface pattern of the polishing pad 2 comprises a plurality of concentric circular grooves 21, wherein the depth and the width of the circular grooves 21 are designed depending upon actual requirements. The defect of the polishing pad 2 lies in that the difference between polishing areas of local regions is excessively large, thus it is hard to achieve the uniformity of the groove area ratio. Moreover, the impurities generated during the polishing process cannot be easily removed from the polishing pad 2, thereby influencing the polishing precision and the lifetime of the polishing pad 2.

Consequently, there is an existing need for a polishing pad having hollow fibers and the method for making the same to solve the above-mentioned problems.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a polishing pad having hollow fibers. The polishing pad comprises a body and a plurality of hollow fibers. The body has a polishing surface. The hollow fibers are located within the body and have an opening on the polishing surface, wherein the hollow area of the section of each hollow fiber is larger than the sectional area of the polishing particles in a polishing slurry. Therefore, the polishing slurry and the polishing particles achieve a thorough circulation on the polishing pad via the hollow fibers, unlike the transmission of polishing slurry in the conventional polishing pad, which is limited by the polishing area ratio occupied by the grooves. Moreover, in the present invention, since the flowability of the polishing slurry and polishing particles is superior, the processing time for the workpiece to be ground is quite uniform and can be estimated and controlled, unlike the processing time for the polishing slurry to be applied to the workpiece to be ground in the conventional polishing pad, which cannot be estimated and controlled.

Another objective of the present invention is to provide a method for making a polishing pad having hollow fibers. The method comprises: (a) providing a plurality of hollow fibers; (b) vertically arranging the hollow fibers on a substrate; (c) forming a body to cover the hollow fibers; and (d) removing the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top view of a first conventional polishing pad having a surface pattern on the surface;

FIG. 2 is a schematic top view of a second conventional polishing pad having a surface pattern on the surface;

FIG. 3 is a schematic cross-sectional view of a polishing pad having hollow fibers according to the present invention;

FIG. 4 is diagram of an SEM photo of the hollow fibers used in the present invention;

FIG. 5 is a schematic cross-sectional view of a polishing pad having hollow fibers according to another embodiment of the present invention; and

FIGS. 6-7 are schematic views of a flow for fabricating the polishing pad having hollow fibers according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a polishing pad having hollow fibers, which is applied in a chemical mechanical polishing (CMP) process to polish or grind a workpiece to be ground. The workpiece to be ground may be, but is not limited to, a semiconductor, a storage medium substrate, an integrated circuit, an LCD flat panel glass, an optical glass or a photoelectric panel.

Referring to FIG. 3, it is a schematic cross-sectional view of a polishing pad having hollow fibers according to the present invention. The polishing pad 3 comprises a body 31 and a plurality of hollow fibers 32. The body 31 has a polishing surface 33. In this embodiment, the material of the body 31 is high solid PU, and the body 31 has a plurality of continuous or discontinuous holes 34 therein. However, the material of the body 31 also can be acryl resin or another resin.

FIG. 4, it is a diagram of an SEM photo of the hollow fibers used in the present invention. The hollow fibers used in the present invention are conventional hollow fibers. Referring to FIG. 3, the hollow fiber 32 is located within the body 31 and has an opening on the polishing surface 33, and the openings of the hollow fibers 32 are distributed uniformly. In this embodiment, the material of the hollow fibers 32 is selected from a group consisting of PP, PET, and Nylon. The ratio of the hollow area of the section of each of the hollow fibers 32 to the total area of the section thereof (hollowed ratio) is 10-30%.

In the present invention, the hollow area of the section of each hollow fiber 32 is larger than the sectional area of the polishing particles (not shown) in a polishing slurry, which allows the polishing slurry and polishing particles to flow within the hollow fibers 32. The polishing slurry and polishing particles thereby achieve a thorough circulation on the polishing pad 3 via the hollow fibers 32, unlike the transmission of the polishing slurry in the conventional polishing pad 1, 2 (FIG. 1 and FIG. 2), which is limited by the polishing area ratio occupied by the grooves. Moreover, in the present invention, since the flowability of the polishing slurry and polishing particles is superior, the processing time for the workpiece to be ground is uniform and can be estimated and controlled, unlike the processing time for the polishing slurry to be applied to the workpiece to be ground in the conventional polishing pad 1, 2 (FIG. 1 and FIG. 2), which cannot be estimated and controlled.

In this embodiment, the openings of the hollow fibers 32 are uniformly distributed, that is, the hollow fibers 32 are uniformly distributed on the polishing surface 33, and the hollow fibers 32 are vertical to the polishing surface 33. However, the openings of the hollow fibers 32 also can be arranged in a particular pattern, for example, arranged in a plurality of concentric circles, or arranged in a “#” shape.

Preferably, in other embodiment, the hollow fibers 32 further protrude from the polishing surface 33, as shown in FIG. 5. The effect of removing the residuals after the grinding process can be achieved in this embodiment by utilizing the toughness characteristic of the hollow fibers 32 themselves.

Preferably, the polishing pad 3 further comprises a plurality of grooves (not shown) located on the polishing surface 33. As seen from the top, the grooves can be a plurality of linear grooves arranged in “#” shape, or a plurality of concentric circular grooves.

The present invention further comprises a method for making the polishing pad 3, which comprises the following steps. First, a plurality of hollow fibers 32 as shown in FIG. 4 is provided. Then, referring to FIG. 6, the hollow fibers 32 are vertically arranged on a substrate 40. In this embodiment, the hollow fibers 32 are arranged on the substrate 40 by using electrostatic adsorption method. In this embodiment, the hollow fibers 32 are vertically distributed on the substrate 40 uniformly. However, the hollow fibers 32 can also be arranged into a particular pattern, for example, into a plurality of concentric circles, or into a “#” shape.

Next, referring to FIG. 7, a body 31 is formed to cover the hollow fibers 32. In this embodiment, the material of the body 31 is a High Solid PU, and the body 31 has a plurality of continuous or discontinuous holes 34 therein. However, the material of the body 31 also can be acryl resin or another resin.

Finally, the substrate 40 is removed, and the polishing pad 3 as shown in FIG. 3 is formed after overturning for 180 degrees.

While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention may not be limited to the particular forms as illustrated, and that all modifications which maintain the spirit and scope of the present invention are within the scope as defined in the appended claims. 

1-10. (canceled)
 11. A method for making a polishing pad having hollow fibers, the method comprising the steps of: (a) providing a plurality of hollow fibers; (b) vertically arranging the hollow fibers on a substrate; (c) forming a body to cover the hollow fibers; and (d) removing the substrate to form a polishing pad, wherein the polishing pad has the body and the hollow fibers and a height of the body is greater than a height of the hollow fibers.
 12. The method as claimed in claim 11, wherein in step (b), the hollow fibers are vertically distributed on the substrate uniformly.
 13. The method as claimed in claim 11, wherein in step (b), the hollow fibers are arranged in a plurality of concentric circles.
 14. The method as claimed in claim 11, wherein in step (b), the hollow fibers are arranged in a “#” shape.
 15. The method as claimed in claim 11, wherein in step (b), the hollow fibers are arranged on the substrate by using an electrostatic adsorption method. 